Re: [MEXT] Issue #18 ["Home Address Option & ICMP / Binding errors"], part 3 of 3: "Receiving Binding Errors"

[Brian Haley <brian.haley at hp.com>]

Hi Charlie,

I might as well comment on all three of these :)

Charles E. Perkins wrote:
> 
> Hello folks,
> 
> Last month, issue #18 showed up without any fanfare on the
> issues tracker list:
>    http://trac.tools.ietf.org/wg/mext/trac/ticket/18
> I'd like to initiate discussion on the points raised as part
> of issue #18.  There are three main points, which can be
> discussed separately.  In this note, I transcribe the
> discussion about the third of the three points.
> 
> =============================================
> 
> Receiving Binding Errors
> 
> In Section 11.3.6. Receiving Binding Error Messages, it is not
> considered that Binding Error Messages can also come from Home
> Agents when acting as a Correspondent Node to its Mobile Nodes
> [see also issue #12]. It is only defined that:
>    "If the mobile node has no upper layer progress information,
>    it MUST remove the (Binding Update List) entry (from the
>    Correspondent Node) and route further communications through
>    the home agent. It MAY also optionally start a return
>    routability procedure (see Section 5.2)."
> 
> If the Correspondent Node is the Home Agent, it is likely that
> there is also no tunnel to route communications through. This
> case may happen if the Home Agent reboots without a persistent
> storage of its Binding Cache.

Will this actually ever happen?  A MN should only ever get a Binding Error from
it's HA in response to a BU, which might have Status set to 2.  Otherwise,
packets are being sent in the MN-HA tunnel, which doesn't use a HAO, which is
what Status value 1 is for, which is what Section 11.3.6 is referring to.

> Proposal: If the Binding Error Message was sent by the Home Agent,
> the Mobile Node SHOULD send a Binding Update to the Home Agent
> according to Section 11.7.1.

I *guess* that's ok, depending on how it's inserted in this section, maybe the
reporter can explain this issue better?

-Brian